Sheet conveyance apparatus

ABSTRACT

A sheet conveyance apparatus includes a conveyance roller, a first rotary member forming a first nip portion conveying a sheet in a first conveyance direction, a rotation axis of the first rotary member being inclined with respect to a rotation axis of the conveyance roller such that a center of one end of the first rotary member is positioned at a different position in the first conveyance direction with respect to a center of the other end, and a second rotary member forming a second nip portion conveying a sheet in a second conveyance direction, a rotation axis of the second rotary member being inclined with respect to the rotation axis of the conveyance roller such that a center of one end of the second rotary member is positioned at a different position in the second conveyance direction with respect to a center of the other end.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a sheet conveyance apparatus conveying sheets.

Description of the Related Art

Hitherto, Japanese unexamined patent application publication No. 2007-145452 proposes a sheet conveyance apparatus having a conveyance roller and two driven rollers that contact the conveyance roller, capable of conveying a sheet while straightening the curl of the sheet. The two driven rollers are supported by a single holder such that the rotation axes of the rollers are parallel.

On the other hand, Japanese unexamined patent application publication No. 2010-195544 discloses a configuration where driven rollers are inclined with respect to a conveyance roller so as to prevent semi-melted toner from attaching to the driven rollers and causing image defects, in a case where the sheet conveyance apparatus is arranged close to a fixing unit.

However, if a configuration is adopted to straighten curls and suppressing toner attachment to the driven rollers by inclining a plurality of driven rollers, which are provided in parallel, with respect to the conveyance roller, end portions of the driven rollers may contact the conveyance roller strongly, causing striated damages to the sheets.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a sheet conveyance apparatus includes a conveyance roller, a first rotary member configured to be rotated in contact with the conveyance roller, and forming a first nip portion, conveying a sheet in a first conveyance direction, together with the conveyance roller, a rotation axis of the first rotary member being inclined with respect to a rotation axis of the conveyance roller such that a center of one end of the first rotary member is positioned at a different position in the first conveyance direction with respect to a center of the other end of the first rotary member in a view from a rotation axis direction of the conveyance roller, and a second rotary member configured to be rotated in contact with the conveyance roller, and forming a second nip portion, conveying a sheet in a second conveyance direction, together with the conveyance roller, the second rotary member being provided downstream of the first rotary member in a rotation direction of the conveyance roller, a rotation axis of the second rotary member being inclined with respect to the rotation axis of the conveyance roller such that a center of one end of the second rotary member is positioned at a different position in the second conveyance direction with respect to a center of the other end of the second rotary member in a view from the rotation axis direction of the conveyance roller.

According to a second aspect of the present invention, a sheet conveyance apparatus includes a conveyance roller, a first rotary member configured to be rotated in contact with the conveyance roller, and forming a first nip portion, conveying a sheet in a first conveyance direction, together with the conveyance roller, and a second rotary member configured to be rotated in contact with the conveyance roller, and forming a second nip portion, conveying a sheet in a second conveyance direction, together with the conveyance roller, the second rotary member being provided downstream of the first rotary member in a rotation direction of the conveyance roller, wherein a rotation axis of the first rotary member and a rotation axis of the second rotary member are inclined with respect to a rotation axis of the conveyance roller, and in a cross section perpendicular to the rotation axis of the conveyance roller, in a case where two areas divided by a virtual line passing a center of one end of the first rotary member and a center of one end of the second rotary member arranged on a same side as the one end of the first rotary member are referred to as a first area and a second area, a center of the other end of the first rotary member is positioned within the first area, and a center of the other end of the second rotary member is positioned within the second area.

According to a third aspect of the present invention, a sheet conveyance apparatus includes a conveyance roller, a first rotary member configured to be rotated in contact with the conveyance roller, and forming a first nip portion, conveying a sheet in a first conveyance direction, together with the conveyance roller, and a second rotary member configured to be rotated in contact with the conveyance roller, and forming a second nip portion, conveying the sheet in a second conveyance direction, together with the conveyance roller, the second rotary member provided downstream of the first rotary member in a rotation direction of the conveyance roller, wherein a rotation axis of the first rotary member and a rotation axis of the second rotary member are not parallel.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general schematic view of a printer according to a first embodiment.

FIG. 2 is a perspective view of a sheet discharge portion according to the first embodiment.

FIG. 3 is a cross-sectional side view of a first sheet conveyance unit according to the first embodiment.

FIG. 4 is a perspective view of the first sheet conveyance unit according to the first embodiment.

FIG. 5 is a side view illustrating an inclination of a first idler roller and a second idler roller according to the first embodiment.

FIG. 6 is a perspective view illustrating the inclination of the first idler roller and the second idler roller according to the first embodiment.

FIG. 7 is a view taken from direction A of FIGS. 5 and 6.

FIG. 8 is a view taken from direction B of FIGS. 5 and 6.

FIG. 9 is a perspective view of a first idler roller and a second idler roller according to the second embodiment.

FIG. 10 is a perspective view of a first idler roller and a second idler roller according to a third embodiment.

FIG. 11 is a perspective view of a first idler roller and a second idler roller according to a fourth embodiment.

FIG. 12A is a perspective view of a holding member according to the first embodiment.

FIG. 12B is a front view of the holding member according to the first embodiment.

FIG. 13A is an explanatory view of the inclination of a discharge roller, the first idler roller and the second idler roller according to the first embodiment.

FIG. 13B is a perspective view of the first idler roller.

FIG. 13C is a perspective view of the second idler roller.

FIG. 14A is a view illustrating the inclination of a discharge roller, the first idler roller and the second idler roller according to the second embodiment.

FIG. 14B is a perspective view of the first idler roller.

FIG. 14C is a perspective view of the second idler roller.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

At first, a first embodiment of the present invention will be described. A printer 100, i.e., image forming apparatus, according to the first embodiment is an electro-photographic laser beam printer. As illustrated in FIG. 1, the printer 100 includes a sheet feeding cassette 1 capable of being inserted to and drawn from a printer main body 100A, an image forming unit 50 forming an image on a sheet fed from the sheet feeding cassette 1, a fixing unit 60, and a sheet discharge portion 70.

When an image forming command is output to the printer 100, an image forming process by the image forming unit 50 is started based on image information entered from an external computer and the like connected to the printer 100. The image forming unit 50 includes a cartridge 5 having a photosensitive drum 6, i.e., an image bearing member, a laser scanner 8, and a transfer roller 7. The laser scanner 8 irradiates a laser beam 9 toward the photosensitive drum 6 based on the entered image information. At this time, the photosensitive drum 6 is charged in advance by a charging roller (not shown), and an electrostatic latent image is formed on the photosensitive drum 6 by irradiating the laser beam 9. Thereafter, an electrostatic latent image is developed by a developing roller (not shown), and a toner image is formed on the photosensitive drum 6.

In parallel with the above-described image forming process, a sheet S supported on the sheet feeding cassette 1 is sent out by a feeding roller 2. The sheet S is separated one by one via a separation unit (not shown). Then, the sheet S is conveyed via an intermediate transfer roller 3 and a conveyance idler roller 4 toward the transfer roller 7. The transfer roller 7, i.e., transfer unit, transfers a toner image formed on the photosensitive drum 6 to the sheet S by having a transfer bias applied thereto.

The sheet S having the toner image transferred from the transfer roller 7 is heated and pressed by the fixing unit 60 composed of a heating roller 10 and a pressure roller 11, and the toner image is fixed. Then, the sheet S is discharged onto a discharge tray 30 by the sheet discharge portion 70 arranged downstream of the fixing unit in a sheet conveyance direction.

Next, the sheet discharge portion 70 will be described in detail. As illustrated in FIG. 2, the sheet discharge portion 70 includes a discharge upper guide 16 and a discharge lower guide 18 constituting a discharge conveyance path 31 (refer to FIG. 3), and a drive shaft 12 a supported rotatably by bearings 17 and 17 press-fit to the discharge upper guide 16. Further, the sheet discharge portion 70 includes a first sheet conveyance unit 80A, i.e., sheet conveyance apparatus, and a second sheet conveyance unit 80B arranged abreast in a width direction orthogonal to the sheet conveyance direction. The first sheet conveyance unit 80A and the second sheet conveyance unit 80B are disposed symmetrically with respect to a center line in the width direction of the discharge conveyance path 31, and in the present embodiment, only the configuration of the first sheet conveyance unit 80A is described, and the configuration of the second sheet conveyance unit 80B will be omitted.

As illustrated in FIGS. 3 and 4, the first sheet conveyance unit 80A includes a discharge roller 12, i.e., conveyance roller, fixed to a drive shaft 12 a, i.e., rotation shaft, and a first idler roller 13 c, i.e., first rotary member, driven by the discharge roller 12. Further, the first sheet conveyance unit 80A includes a second idler roller 14 c, i.e., second rotary member, arranged downstream in the sheet conveyance direction of the first idler roller 13 c, and driven by the discharge roller 12. The first sheet conveyance unit 80A includes, in a rotation shaft direction of the discharge roller 12, a first rotation shaft 13, i.e., first shaft portion, extending from both ends of the first idler roller 13 c, a second rotation shaft 14, i.e., second shaft portion, extending from both ends of the second idler roller 14 c, and a holding member 15, i.e., holder, rotatably supporting the first rotation shaft 13 and the second rotation shaft 14.

A perspective view of the holding member 15 illustrated in FIG. 12A is referred to in describing a configuration of the holding member 15. The holding member 15 includes a first side wall 15 a, i.e., first supporting portion, and a second side wall 15 b, i.e., second supporting portion, disposed in parallel with the first side wall 15 a. The first side wall 15 a includes supporting portions 1513 a and 1514 a respectively rotatably supporting one end portion 13 a of the first rotation shaft 13 and one end portion 14 a of the second rotation shaft 14 arranged on the same side as the one end portion 13 a. The second side wall 15 b includes supporting portions 1513 b and 1514 b respectively rotatably supporting the other end portion 13 b of the first rotation shaft 13 and the other end portion 14 b of the second rotation shaft 14 arranged on the same side as the other end portion 13 b. A virtual line L13 passing the supporting portions 1513 a and 1513 b is not parallel with a virtual line m14 passing a supporting portion 1514 a and a supporting portion 1514 b.

FIG. 12B illustrates the holding member 15 viewed from a direction perpendicular to the first side wall 15 a. The supporting portions 1513 a and 1513 b are arranged coaxially, whereas the supporting portions 1514 a and 1514 b are arranged non-coaxially. In other words, when seen from the direction perpendicular to the first side wall 15 a, the supporting portions 1513 a and 1513 b are arranged at positions where the center portions are mutually overlapped, whereas the supporting portions 1514 a and 1514 b are arranged at positions where the center portions are not overlapped. The holding member 15 is designed such that the virtual line L13 is inclined with respect to the drive shaft 12 a of the discharge roller 12.

The holding member 15 is attached movably in a substantially vertical direction with respect to the discharge lower guide 18, and a spring 19 is arranged in a compressed manner between the discharge lower guide 18 and the holding member 15. The spring 19 biases the first idler roller 13 c and the second idler roller 14 c via the holding member 15 to be in pressure contact with the discharge roller 12. Further, the spring 19 is arranged such that the first idler roller 13 c and the second idler roller 14 c press a substantially center position in an axial direction of the discharge roller 12.

A control unit (not shown) is provided in the printer main body 100A, and the drive shaft 12 a is rotated by the control unit driving a drive source (not shown). When the drive shaft 12 a rotates, the discharge roller 12 fixed to the drive shaft 12 a rotates, and along with the rotation of the discharge roller 12, the first and second idler rollers 13 c and 14 c are driven to rotate.

Next, a more detailed arrangement of the first and second idler rollers 13 c and 14 c will be described with reference to FIGS. 5 through 8. FIG. 5 is a side view of the discharge roller 12, the first idler roller 13 c and the second idler roller 14 c seen from a rotational axis line L1 of the discharge roller 12. FIG. 7 is a view seen from the direction of arrow A of FIGS. 5 and 6, and FIG. 8 is a view seen from the direction of arrow B of FIGS. 5 and 6. The direction of arrow A is a direction perpendicular to a contact surface F1 between the discharge roller 12 and the first idler roller 13 c, and the direction of arrow B is a direction perpendicular to a contact surface F2 between the discharge roller 12 and the second idler roller 14 c.

As illustrated in FIG. 7, the first idler roller 13 c is arranged such that the first rotation shaft 13 is inclined with respect to the rotational axis line L1 of the discharge roller 12. In other words, a rotational axis line L2 of the first idler roller 13 c is inclined for angle θ with respect to the rotational axis line L1 of the discharge roller 12.

Further, as illustrated in FIG. 8, the second idler roller 14 c is arranged such that the second rotation shaft 14 is inclined with respect to the rotational axis line L1 of the discharge roller 12 and the first rotation shaft 13. In other words, a rotational axis line L3 of the second idler roller 14 c is inclined by angle θ with respect to the rotational axis line L1 of the discharge roller 12. In the present embodiment, the inclination angles of the rotational axis lines L2 and L3 with respect to the rotational axis line L1 are the same angle θ, but the angles can differ as long as the transfer of the sheet S is not hindered. Further, the inclination of the first idler roller 13 c and the second idler roller 14 c are set in accordance with the positions of the supporting portions 1513 a, 1513 b, 1514 a and 1514 b of the holding member 15. The angle θ should preferably be 1 degree or greater and 3 degrees or smaller.

Now, as illustrated in FIGS. 5 and 6, a plane parallel to the rotational axis line L1 of the discharge roller 12 and including the contact surfaces F1 and F2 is defined as a reference plane P. The first idler roller 13 c and the second idler roller 14 c are arranged to be inclined toward a same direction with respect to a width direction when viewed from a direction orthogonal to the reference plane P. The one end portion 13 a positioned upstream in the sheet conveyance direction of the first rotation shaft 13 is arranged closer to the reference plane P than to the other end portion 13 b positioned downstream. The one end portion 14 a positioned upstream in the sheet conveyance direction of the second rotation shaft 14 is arranged farther from the reference plane P than the other end portion 14 b positioned downstream.

As described, according to the present embodiment, the first idler roller 13 c and the second idler roller 14 c are respectively independently inclined with respect to the discharge roller 12. Thereby, the first idler roller 13 c and the second idler roller 14 c are in contact at a center position in the width direction with the discharge roller 12. In other words, the first idler roller 13 c and the second idler roller 14 c contact the discharge roller 12 symmetrically with the center position in the width direction set as reference, such that the sheet S can be conveyed stably. Further, damages such as creases of the sheet can be reduced. Furthermore, the present arrangement prevents toner from attaching to the first and second idler rollers 13 c and 14 c, and can straighten the curls of the sheet.

Next, how the first idler roller 13 c is inclined with respect to the discharge roller 12 and how the second idler roller 14 c is inclined with respect to the discharge roller 12 will be described in detail with reference to FIGS. 13A, 13B and 13C.

FIG. 13A is a view illustrating the discharge roller 12, the first idler roller 13 c and the second idler roller 14 c from the direction of the rotation axis of the discharge roller 12. In FIG. 13A, one end face 13 cF, i.e., one end, of the first idler roller 13 c is illustrated by a solid line, and the other end face 13 cB, i.e., the other end, is illustrated by a dashed line. A center of one end face 13 cF of the first idler roller 13 c is referred to as C1, and a center of the other end face 13 cB is referred to as C1′. A sheet is conveyed by a nip portion N1, i.e., first nip portion, formed by the discharge roller 12 being in contact with the first idler roller 13 c. A conveyance direction D1, i.e., first conveyance direction, of a sheet at the nip portion N1 is a direction perpendicular to a line passing a center of the rotation shaft direction of the first idler roller 13 c, i.e., center of a line segment connecting C1 and C1′, and a center of rotation of the discharge roller 12, when seen from the rotation shaft direction of the discharge roller 12.

Similarly, in the second idler roller 14 c, one end face 14 cF is illustrated by a solid line, and the other end face 14 cB is illustrated by a dashed line. A center of one end face 14 cF of the second idler roller 14 c is referred to as C2, and a center of the other end face 14 cB is referred to as C2′. FIGS. 13B and 13C are perspective views of the first idler roller 13 c and the second idler roller 14 c. A sheet is conveyed by a nip portion N2, i.e., second nip portion, formed by the discharge roller 12 being in contact with the second idler roller 14 c. A conveyance direction D2, i.e., second conveyance direction, of a sheet at the nip portion N2 is a direction perpendicular to a line passing a center of the rotation shaft direction of the second idler roller 14 c, i.e., center of a line segment connecting C2 and C2′, and a center of rotation of the discharge roller 12, when seen from the rotation shaft direction of the discharge roller 12.

A rotation shaft of the first idler roller 13 c is inclined in the following manner with respect to the rotation shaft of the discharge roller 12. When seen from the rotation shaft direction of the discharge roller 12, the center C1′ of the other end face 13 cB of the rotation shaft direction of the first idler roller 13 c is shifted downstream with respect to the center C1 of one end face 13 cF of the sheet conveyance direction D1 of the nip portion N1. The rotation shaft of the second idler roller 14 c is inclined in the following manner with respect to the rotation shaft of the discharge roller 12. When seen from the rotation shaft direction of the discharge roller 12, the center C2′ of the other end face 14 cB of the rotation shaft direction of the second idler roller 14 c is shifted downstream with respect to the center C2 of the one end face 14 cF of the sheet conveyance direction D2 of the nip portion N2.

How the first idler roller 13 c and the second idler roller 14 c are inclined with respect to the discharge roller 12 will be described with reference to FIGS. 14A, 14B and 14C.

FIG. 14A is a view illustrating the discharge roller 12, the first idler roller 13 c and the second idler roller 14 c from the rotation shaft direction of the discharge roller 12. In FIG. 14A, one end face 13 cF of the first idler roller 13 c is illustrated by a solid line, and the other end face 13 cB is illustrated by a dashed line. The center of one end face 13 cF of the first idler roller 13 c is referred to as C1, and the center of the other end face 13 cB is referred to as C1′.

Similarly, regarding the second idler roller 14 c, one end face 14 cF is illustrated by a solid line, and the other end face 14 cB is illustrated by a dashed line. The center of one end face 14 cF of the second idler roller 14 c is referred to as C2, and the center of the other end face 14 cB is referred to as C2′. FIGS. 14B and 14C are perspective views of the first idler roller 13 c and the second idler roller 14 c. The center C1 of the one end face 13 cF of the first idler roller 13 c and the center C2 of the one end face 14 cF of the second idler roller 14 c are arranged on the same side in the rotation shaft direction of the discharge roller 12.

Now, in a cross section perpendicular to the rotation shaft of the discharge roller 12, areas divided by a virtual line v12 passing the centers C1 and C2 are referred to as a first area A1 and a second area A2. The first idler roller 13 c and the second idler roller 14 c are respectively inclined with respect to the discharge roller 12 such that the center C1′ of the other end face 13 cB of the first idler roller 13 c is positioned within the first area A1 and the center C2′ of the other end face 14 cB of the second idler roller 14 c is positioned within the second area A2.

According further to the present embodiment, as described above, the first and second sheet conveyance units 80A and 80B are arranged symmetrically with respect to a center line, i.e., a center portion of the discharge roller 12 in the rotation axis direction thereof, in the width direction of the discharge conveyance path 31. The conveyance directions of the first and second idler rollers 13 c and 14 c of the first and second sheet conveyance units 80A and 80B are respectively directed outward by predetermined angles with respect to the sheet conveyance direction. In other words, the sheet S will be pulled outward in the width direction while the sheet S is being conveyed by the sheet discharge portion 70, so that skew feeding and forming of creases on the sheet S can be prevented.

In the present embodiment, the sheet discharge portion 70 has a pair of sheet conveyance units 80A and 80B, but the present invention is not restricted to this configuration, and two or more pairs of sheet conveyance units arranged in parallel in the width direction can also be adopted.

Second Embodiment

Next, a second embodiment of the present invention will be described with reference to FIG. 9. The second embodiment has changed the configuration of the first and second idler rollers 13 c and 14 c of the first embodiment, and the configurations similar to the first embodiment are either not illustrated or assigned with the same reference numbers.

A first idler roller 23 according to the present embodiment includes a disk-shaped first disk portion 23 a and second disk portion 23 b arranged in parallel in the axial direction, and the first and second disk portions 23 a and 23 b are fixed to the first rotation shaft 13. A second idler roller 24 includes a disk-shaped third disk portion 24 a and fourth disk portion 24 b arranged in parallel in the shaft direction, and the third and fourth disk portions 24 a and 24 b are fixed to the second rotation shaft 14.

The first and second disk portions 23 a and 23 b are arranged symmetrically with respect to a center position in the width direction of the discharge roller 12. The third and fourth disk portions 24 a and 24 b are arranged symmetrically with respect to a center portion in the width direction of the discharge roller 12. That is, concave portions 23 c and 24 c not in contact with the discharge roller 12, i.e., first and second concave portions, are respectively formed in center portions between the first and second disk portions 23 a and 23 b and between the third and fourth disk portions 24 a and 24 b. The inclination of the first rotation shaft 13 and the second rotation shaft 14 with respect to the rotational axis line L1 of the discharge roller 12 is set similarly as the first embodiment.

Therefore, the first and second disk portions 23 a and 23 b contact the discharge roller 12 symmetrically with respect to the center position in the width direction of the roller 12. Further, the third and fourth disk portions 24 a and 24 b contact the discharge roller 12 symmetrically with respect to the center position in the width direction of the roller 12. Thereby, the discharge roller 12, the first idler roller 23 and the second idler roller 24 can convey the sheet S stably and more smoothly, and damages such as creases on the sheet can be reduced.

In the present embodiment, both the first and second idler rollers 23 and 24 have two disk portions, but it is possible to adopt a configuration where only one of the idler rollers 23 or 24 has two disk portions, or where three or more disk portions are formed.

Third Embodiment

Next, a third embodiment of the present invention will be described with reference to FIG. 10. The third embodiment has changed the configuration of the first and second idler rollers 13 c and 14 c of the first embodiment, and similar configurations as the first or second embodiment will either be not shown or denoted with the same reference numbers. The effects similar to the second embodiment will not be described.

A first idler roller 33 according to the present embodiment has disk-shaped first disk portion 33 a, second disk portion 33 b, fifth disk portion 33 c and sixth disk portion 33 d that are arranged in parallel in the axial direction. The first and second disk portions 33 a and 33 b are arranged symmetrically with respect to a center position in the width direction of the discharge roller 12. The fifth and sixth disk portions 33 c and 33 d are arranged symmetrically with respect to a center position in the width direction of the discharge roller 12. The inclination of the first rotation shaft 13 and the second rotation shaft 14 with respect to a rotational axis line L1 of the discharge roller 12 is set similarly as the first embodiment.

The third and fourth disk portions 24 a and 24 b constituting the second idler roller 24 are arranged in dislocated positions in the axial direction with respect to the first disk portion 33 a, the second disk portion 33 b, the fifth disk portion 33 c and the sixth disk portion 33 d. Further, the third and fourth disk portions 24 a and 24 b are overlapped in a radial direction with respect to the first disk portion 33 a, the second disk portion 33 b, the fifth disk portion 33 c and the sixth disk portion 33 d. More specifically, the third disk portion 24 a is arranged to be inserted between the first disk portion 33 a and the fifth disk portion 33 c, and the fourth disk portion 24 b is arranged to be inserted between the second disk portion 33 b and the sixth disk portion 33 d.

According to this arrangement, the outer diameters of the first disk portion 33 a, the second disk portion 33 b, the third disk portion 24 a, the fourth disk portion 24 b, the fifth disk portion 33 c and the sixth disk portion 33 d can be increased. Thereby, the leading edge of the sheet S can enter the disk portions at a shallow angle, so that the occurrence of sheet jam or damages to the leading edge of the sheet can be reduced.

The present embodiment adopts a configuration where the first idler roller 33 includes four disk portions and the second idler roller 24 includes two disk portions, but the number of disk portions can be set to any arbitrary number.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be described with reference to FIG. 11. The fourth embodiment has changed the configuration of the first and second idler rollers 13 c and 14 c of the first embodiment, and similar configurations as the first embodiment are either not illustrated or referred to by the same reference numbers. Further, the similar effects as the second or third embodiments will not be described.

A first idler roller 43 according to the present embodiment includes two center disk portions 43 a and 43 a disposed at a center portion in a width direction, and two end disk portions 43 b and 43 b disposed at both end portions in the width direction. The end disk portions 43 b and 43 b are set to have smaller outer diameters than the center disk portions 43 a and 43 a, and the first idler roller 43 is designed to be barrel-shaped as a whole.

Moreover, the second idler roller 44 has two center disk portions 44 a and 44 a provided at a center portion in the width direction and two end disk portions 44 b and 44 b provided at both end portions in the width direction. The end disk portions 44 b and 44 b are designed to have smaller outer diameters than the center disk portions 44 a and 44 a, and as a whole, the second idler roller 44 is barrel-shaped. The inclination of the first rotation shaft 13 and the second rotation shaft 14 with respect to the rotational axis line of the discharge roller 12 is set similarly as the first embodiment.

According to the present embodiment, the first idler roller 43 is barrel-shaped as a whole, so that the sheet S expanded between the fixing unit 60 and the sheet discharge portion 70 can be prevented from being in contact locally with the end portion of the first idler roller 43. That is, since the first idler roller 43 is arranged in an inclined manner with respect to the discharge roller 12, the first idler roller 43 contacts the sheet with stronger force at the upstream side in the sheet conveyance direction than the downstream side of the roller 43. However, since the end disk portions 44 b and 44 b are set to have smaller outer diameters than the center disk portions 44 a and 44 a according to the present embodiment, the sheet can be prevented from being damaged.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2015-136302, filed Jul. 7, 2015, and Japanese Patent Application No. 2016-112008, filed Jun. 3, 2016, which are hereby incorporated by reference herein in their entirety. 

What is claimed is:
 1. A sheet conveyance apparatus conveying a sheet, the sheet conveyance apparatus comprising: a conveyance roller; a first rotary member configured to be rotated by a rotation of the conveyance roller, and form a first nip portion, together with the conveyance roller, in which the sheet is conveyed in a first conveyance direction, a rotation axis of the first rotary member being inclined with respect to a rotation axis of the conveyance roller such that when viewed in a rotation axis direction of the conveyance roller, a rotation center of a first longitudinal end of the first rotary member is arranged in the first conveyance direction at a position different from a position at which a rotation center of a second longitudinal end of the first rotary member is arranged, and a first virtual line passing through the rotation center of the first longitudinal end of the first rotary member and the rotation center of the second longitudinal end of the first rotary member extends in a direction along the first conveyance direction; and a second rotary member configured to be rotated by a rotation of the conveyance roller, and form a second nip portion, together with the conveyance roller, in which the sheet is conveyed in a second conveyance direction, the second rotary member being provided downstream of the first rotary member in a rotation direction of the conveyance roller, a rotation axis of the second rotary member being inclined with respect to the rotation axis of the conveyance roller such that when viewed in the rotation axis direction of the conveyance roller, a rotation center of a third longitudinal end of the second rotary member is arranged, in the second conveyance direction, at a position different from a position at which a rotation center of a fourth longitudinal end of the second rotary member is arranged, and a second virtual line passing through the rotation center of the third longitudinal end of the second rotary member and the rotation center of the fourth longitudinal end of the second rotary member extends in a direction along the second conveyance direction, wherein one sheet is conveyed simultaneously by both the first nip portion and the second nip portion.
 2. The sheet conveyance apparatus according to claim 1, further comprising a holder holding the first rotary member and the second rotary member in a rotatable manner such that the rotation axis of the first rotary member and the rotation axis of the second rotary member are not parallel.
 3. The sheet conveyance apparatus according to claim 2, wherein the first rotary member comprises a first shaft portion extending from both ends in a rotation axis direction thereof, the second rotary member comprises a second shaft portion extending from both ends in a rotation axis direction thereof, and the holder comprises a first supporting portion supporting one end of the first shaft portion and one end of the second shaft portion arranged on a same side as the one end of the first shaft portion, and a second supporting portion supporting the other end of the first shaft portion and the other end of the second shaft portion arranged on a same side as the other end of the first shaft portion.
 4. The sheet conveyance apparatus according to claim 1, wherein an angle formed between the rotation axis of the conveyance roller and the rotation axis of the first rotary member is one degree or greater and three degrees or less, and an angle formed between the rotation axis of the conveyance roller and the rotation axis of the second rotary member is one degree or greater and three degrees or less.
 5. The sheet conveyance apparatus according to claim 1, wherein the first rotary member and the second rotary member are inclined around a center portion of the conveyance roller in the rotation axis direction thereof.
 6. The sheet conveyance apparatus according to claim 5, wherein a center portion of the first rotary member in a rotation axis direction thereof comprises a first concave portion not in contact with the conveyance roller, and a center portion of the second rotary member in a rotation axis direction thereof comprises a second concave portion not in contact with the conveyance roller.
 7. A sheet conveyance apparatus conveying a sheet, the sheet conveyance apparatus comprising: a conveyance roller; a first rotary member configured to be rotated by a rotation of the conveyance roller, and form a first nip portion, together with the conveyance roller, in which the sheet is conveyed in a first conveyance direction, the first rotary member including a first shaft portion extending from both ends in a rotation axis direction of the first rotary member; a second rotary member configured to be rotated by a rotation of the conveyance roller, and form a second nip portion, together with the conveyance roller, in which the sheet is conveyed in a second conveyance direction, the second rotary member including a second shaft portion extending from both ends in a rotation axis direction of the second rotary member; and a holder configured to hold the first rotary member and the second rotary member rotatably, the holder including a first supporting portion supporting one end of the first shaft portion, a second supporting portion supporting the other end of the first shaft portion, a third supporting portion supporting one end of the second shaft portion, and a fourth supporting portion supporting the other end of the second shaft portion, wherein when viewed in a rotation axis direction of the conveyance roller, a center of the first supporting portion is arranged, in the first conveyance direction, at a position different from a position at which a center of the second supporting portion is arranged, and a center of the third supporting portion is arranged, in the second conveyance direction, at a position different from a position at which a center of the fourth supporting portion is arranged, and wherein one sheet is conveyed simultaneously by both the first nip portion and the second nip portion.
 8. The sheet conveyance apparatus according to claim 7, wherein when viewed in the rotation axis direction of the conveyance roller, a first virtual line passing through the center of the first supporting portion and the center of the second supporting portion extends along the first conveyance direction, and a second virtual line passing through the center of the third supporting portion and the center of the fourth supporting portion extends along the second conveyance direction.
 9. The sheet conveyance apparatus according to claim 7, wherein a rotation axis of the first rotary member and a rotation axis of the second rotary member are not parallel.
 10. The sheet conveyance apparatus according to claim 7, wherein an angle formed between a rotation axis of the conveyance roller and a rotation axis of the first rotary member is one degree or greater and three degrees or less, and an angle formed between the rotation axis of the conveyance roller and a rotation axis of the second rotary member is one degree or greater and three degrees or less.
 11. The sheet conveyance apparatus according to claim 7, wherein the first rotary member and the second rotary member are inclined around a center portion of the conveyance roller in the rotation axis direction thereof.
 12. The sheet conveyance apparatus according to claim 11, wherein a center portion of the first rotary member in the rotation axis direction thereof comprises a first concave portion not in contact with the conveyance roller, and a center portion of the second rotary member in the rotation axis direction thereof comprises a second concave portion not in contact with the conveyance roller. 